Production method of aminopyrimidine compound

ABSTRACT

Aminopyrimidine compounds represented by formula (3) may be efficiently prepared by reacting an azlactone compound represented by formula (1) with an amidine compound represented by formula (2) or a salt thereof: 
     
       
         
         
             
             
         
       
     
     wherein R 1 , R 2  and M are as defined in the specification.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 11/081,631, filed on Mar. 17, 2005, and claims priority toJapanese Patent Application No. 77263/2004, filed on Mar. 17, 2004,which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to novel methods for producingaminopyrimidine compounds which are useful as intermediates forproducing various compounds having pharmacological activity. The presentinvention also relates to certain novel aminopyrimidine compounds.

2. Discussion of the Background

Aminopyrimidine compounds represented by formula (3):

wherein R¹ is an alkyl group optionally having substituents or anaralkyl group optionally having substituents; and R² is an alkyl groupoptionally having substituents, an aryl group optionally havingsubstituents, an aralkyl group optionally having substituents, or agroup represented by the formula (a), the formula (b), or the formula(c):

wherein R³ is an alkyl group optionally having substituents, an arylgroup optionally having substituents, or an aralkyl group optionallyhaving substituents; and R⁴ is a hydrogen atom, an alkyl groupoptionally having substituents, an aryl group optionally havingsubstituents, or an aralkyl group optionally having substituents, areuseful as intermediates for various compounds having pharmacologicalactivity, such as anticancer agents, NK1 antagonists, elastaseinhibitors and the like (see, e.g., U.S. Pat. No. 6,380,206 andWO02/42280, which are incorporated herein by reference in theirentireties).

It has long been known to introduce an amino group into the 5-positionof pyrimidine by introducing a nitro group into uracil and then reducingthe same (see, J. Chem. Soc., pp. 1565-1570 (1951)).

However, since nitro compounds are generally feared due to the risk ofexplosion, they are not necessarily suitable for an industrialproduction method. In addition, since uracil derivatives have a carbonylgroup at both the 2-position and the 4-position, regioselectiveintroduction of a substituent into the 2-position or the 4-position isknown to be difficult (see, J. Chem. Soc. Perk. Trans. 1, 17), pp.919-922 (1992), EP 647639A, and Tetrahedron, vol. 58 (11), pp. 2147-2153(2002)).

As a method of producing an aminopyrimidine compound using a compoundother than uracil as a starting material, for example, a method shown inthe following reaction scheme has been reported (see, J. Chem. Soc.,Perk. Trans. 1, (7), pp. 1659-1664 (1992)):

wherein Ph is a phenyl group, Et is an ethyl group, and Bz is a benzoylgroup.

According to this method, however, the amino-protecting group at the5-position is a benzoyl group, which requires severe conditions fordeprotection, such as use of a strong base or a strong acid andrefluxing for a long time, which in turn limits the types of groups thatcan be introduced into the compound. Thus, this compound is notnecessarily satisfactory for use as an intermediate compound for apharmaceutical product, and a production method capable of introducing aprotecting group that can be removed under milder conditions has beendesired. In contrast, when an amino group at the 5-position of anaminopyrimidine compound is protected with an aliphatic acyl group,deprotection can be performed under comparatively mild conditions.However, a compound in which 2-phenyl-4-ethoxymethylene-azlactone, whichis a starting material to be used for this reaction, contains analiphatic group at the 2-position can be obtained only in acomparatively low yield (see, WO03/106434).

A different production method comprises reacting glycine ethyl esterwith ethyl formate and sodium methoxide to give an ethyl-α-formyl-formylglycinate sodium salt, and reacting this salt with an acid addition saltof amidine in methanol to give formylaminopyrimidine (see, Collect.Czech Chem. Comm., vol. 51(1), pp. 215-233 (1986)). As regards thisproduction method, however, there is no report on an aminopyrimidinecompound, in which an amino group at the 5-position is protected with analiphatic acyl group.

Thus, there remains a need for an improved method for producingaminopyrimidine compounds which are useful as intermediates forproducing various compounds having pharmacological activity. There alsoremains a need for novel aminopyridine compounds which are useful asintermediates for producing various compounds having pharmacologicalactivity.

SUMMARY OF THE INVENTION

Accordingly, it is one object of the present invention to provide novelmethods for producing a compound represented by formula (3).

It is another object of the present invention to provide novel methodsfor producing a compound represented by formula (3) which are efficient.

It is another object of the present invention to provide novelaminopyridine compounds which are useful as intermediates for producingvarious compounds having pharmacological activity.

It is another object of the present invention to provide novel methodsof preparing antineoplastic agents.

These and other objects, which will become apparent during the followingdetailed description, have been achieved by the inventors' discoverythat an aminopyrimidine compound represented by formila (3) can beefficiently obtained by reacting an azlactone compound represented byformula (1), which is described below, as a starting material with anamidine compound represented by formula (2), which is described below,or a salt thereof.

Thus, the present invention provides the following:

(1) A method for producing an aminopyridine compound represented byformula (3):

wherein R¹ is an alkyl group optionally having one or more substituentsor an aralkyl group optionally having one or more substituents; and R²is an alkyl group optionally having one or more substituents, an arylgroup optionally having one or more substituents, an aralkyl groupoptionally having one or more substituents, or a group represented bythe formula (a), the formula (b), or the formula (c):

wherein R³ is an alkyl group optionally having one or more substituents,an aryl group optionally having one or more substituents, or an aralkylgroup optionally having one or more substituents; and R⁴ is a hydrogenatom, an alkyl group optionally having one or more substituents, an arylgroup optionally having one or more substituents, or an aralkyl groupoptionally having one or more substituents.

wherein said method comprises reacting a azlactone compound representedby formula (1):

wherein M is a hydrogen atom or an alkali metal atom; a wavy lineindicates a cis form, a trans form, or a mixture thereof; and R¹ is asdefined above, with an amidine compound represented by formula (2):

wherein R² is as defined above, or a salt thereof.

(2) The method of the above-mentioned (1), wherein R¹ is a linear orbranched chain alkyl group having 1 to 20 carbon atoms, which optionallyhas one or more substituents, or an aralkyl group optionally having oneor more substituents, wherein the aryl moiety in said aralkyl group isan aryl group having 6 to 12 carbon atoms and the alkyl moiety in saidaralkyl group is a linear or branched chain alkyl group having 1 to 6carbon atoms.

(3) The method of the above-mentioned (2), wherein R¹ is a methyl group,an ethyl group, or a benzyl group.

(4) The method of the above-mentioned (1), wherein R² is a linear orbranched chain alkyl group having 1 to 20 carbon atoms, which optionallyhas one or more substituents, an aryl group having 6 to 20 carbon atoms,which optionally has one or more substituents, an aralkyl groupoptionally having one or more substituents, wherein the aryl moiety insaid aralkyl group is an aryl group having 6 to 12 carbon atoms and thealkyl moiety in said aralkyl group is a linear or branched chain alkylgroup having 1 to 6 carbon atoms, or a group represented by the formula(a), the formula (b), or the formula (c):

wherein R³ is a linear or branched chain alkyl group having 1 to 20carbon atoms, which optionally has one or more substituents, an arylgroup having 6 to 20 carbon atoms, which optionally has one or moresubstituents, or an aralkyl group optionally having one or moresubstituents, wherein the aryl moiety in said aralkyl group is an arylgroup having 6 to 12 carbon atoms and the alkyl moiety in said aralkylgroup is a linear or branched chain alkyl group having 1 to 6 carbonatoms, and R⁴ is a hydrogen atom, a linear or branched chain alkyl grouphaving 1 to 20 carbon atoms, which optionally has one or moresubstituents, an aryl group having 6 to 20 carbon atoms, whichoptionally has one or more substituents, or an aralkyl group optionallyhaving one or more substituents, wherein the aryl moiety in said aralkylgroup is an aryl group having 6 to 12 carbon atoms and the alkyl moietyin said aralkyl group is a linear or branched chain alkyl group having 1to 6 carbon atoms.

(5) The method of the above-mentioned (4), wherein R² is a methyl group,an ethyl group, a phenyl group, a chlorophenyl group, a tolyl group, abenzyl group, a methoxy group, a methylthio group, or a dimethylaminogroup.

(6) The method of the above-mentioned (1′, wherein M is at least onealkali metal atom selected from the group consisting of a potassiumatom, a sodium atom, a lithium atom, and mixtures thereof.

(7) The method of the above-mentioned (1), wherein the aminopyrimidinecompound is at least one member selected from the group consisting2-methoxy-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine;2-methoxy-6-oxo-5-acetylamino-1,6-dihydropyrimidine;2-methylthio-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine;2-methylthio-6-oxo-5-acetylamino-1,6-dihydropyrimidine;2-dimethylamino-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine;2-phenyl-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine; and mixturesthereof.

(8) An aminopyrimidine compound represented by formula (4):

wherein R¹ is an alkyl group optionally having one or more substituentsor an aralkyl group optionally having one or more substituents; and R³is an alkyl group optionally having one or more substituents, an arylgroup optionally having one or more substituents or an aralkyl groupoptionally having one or more substituents, or a salt thereof.

(9) The aminopyrimidine compound of the above-mentioned (8), wherein R¹is a linear or branched chain alkyl group having 1 to 20 carbon atoms,which optionally has one or more substituents, or an aralkyl groupoptionally having one or more substituents, wherein the aryl moiety insaid aralkyl group is an aryl group having 6 to 12 carbon atoms and thealkyl moiety in said aralkyl group is a linear or branched chain alkylgroup having 1 to 6 carbon atoms, or a salt thereof.

(10) The aminopyrimidine compound of the above-mentioned (9), wherein R¹is a methyl group, an ethyl group, or a benzyl group, or a salt thereof.

(11) The aminopyrimidine compound of the above-mentioned (8), wherein R³is a linear or branched chain alkyl group having 1 to 20 carbon atoms,which optionally has one or more substituents, an aryl group having 6 to20 carbon atoms, which optionally has one or more substituents, or anaralkyl group optionally having one or more substituents, wherein thearyl moiety in said aralkyl group is an aryl group having 6 to 12 carbonatoms and the alkyl moiety in said aralkyl group is a linear or branchedchain alkyl group having 1 to 6 carbon atoms, or a salt thereof.

(12) The aminopyrimidine compound of the above-mentioned (11), whereinR³ is a methyl group, an ethyl group, a phenyl group, a chlorophenylgroup, a tolyl group, or a benzyl group, or a salt thereof.

(13) The aminopyrimidine compound of the above-mentioned (8), which isselected from the group consisting of2-methoxy-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine and2-methoxy-6-oxo-5-acetylamino-1,6-dihydropyrimidine, or a salt thereof.

The aminopyrimidine compound represented by formula (3) in the presentinvention can be, when an aminopyrimidine compound represented byfollowing formulae (3a) or (3b), for example, selectively aminated atthe 2-position (see, J. Heterocyclic Chem., vol. 19(5), pp. 1117-1124(1982) and J. Chem. Soc., Perk. Trans. 1, (7), pp. 1659-1664 (1991), andcan also be selectively chlorinated at the 4-position (see, ResearchDisclosure, 452068, 10 Dec. 2001 and Ger. Offen., 3423622, 1986).Therefore, various substituents can be introduced into the 2-positionand the 4-position of the aminopyrimidine compound to give variouscompounds:

wherein R¹, R³ and R⁴ are as defined above and alkyl is an alkyl group.

Thus, according to the present invention, an aminopyrimidine compoundrepresented by the above-mentioned formula (3), which is useful as anintermediate for producing various compounds having a pharmacologicalactivity, can be efficiently produced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The definitions of the symbols used in the present invention are asfollows.

In the formulae of the present invention, R¹ is an alkyl groupoptionally having one or more substituents or an aralkyl groupoptionally having one or more substituents. In the formulae of thepresent invention; moreover, R² is an alkyl group optionally having oneor more substituents, an aryl group optionally having one or moresubstituents, or a group represented by the formula (a), the formula(b), or the formula (c):

In the formula (a), the formula (b) and the formula (c), R³ is an alkylgroup optionally having one or more substituents, an aryl groupoptionally having one or more substituents or an aralkyl groupoptionally having one or more substituents; and R⁴ is a hydrogen atom,an alkyl group optionally having one or more substituents, an aryl groupoptionally having one or more substituents or an aralkyl groupoptionally having one or more substituents. Particularly, a grouprepresented by the formula (a) or (b) is preferable.

As the “alkyl group” for R¹, R², R³ or R⁴, a linear or branched chainalkyl group preferably having 1 to 20, more preferably 1 to 7, carbonatoms can be mentioned. Specifically, for example, alkyl groups such asa methyl group, an ethyl group, an n-propyl group, an isopropyl group,an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butylgroup, a lauryl group, and the like can be mentioned. Of these, a methylgroup and an ethyl group are preferable.

The alkyl group is optionally substituted by one or more substituentsbelow. As the substituent here, for example, a linear or branched chainalkoxy group (carbon number: 1 to 6, e.g., methoxy group), a halogenatom (e.g., chlorine atom, fluorine atom, and the like), a hydroxylgroup, and the like can be mentioned.

The “aralkyl group” for R¹, R², R³ or R⁴ is an aralkyl group wherein thearyl moiety is preferably an aryl group having 6 to 12, more preferably6 to 8, carbon atoms and the alkyl moiety is preferably a linear orbranched chain alkyl group having 1 to 6, more preferably 1 to 3, carbonatoms. As a specific example of the aralkyl group, a benzyl group ispreferable.

The aralkyl group is optionally substituted by one or more substituentsbelow. As the substituents here, for example, a nitro group, a linear orbranched chain alkoxy group (carbon number: 1 to 6, e.g.: methoxygroup), a halogen atom (e.g., chlorine atom, fluorine atom, and thelike), a hydroxyl group, and the like can be mentioned.

As the “aryl group” for R¹, R², R³ or R⁴, an aryl group preferablyhaving 6 to 20, more preferably 6 to 8, carbon atoms can be mentioned.The aryl group is optionally substituted by one or more substituentsbelow. As the substituents here, for example, a nitro group, a linear orbranched chain alkoxy group (carbon number: 1 to 6, e.g., methoxygroup), a halogen atom (e.g., chlorine atom, fluorine atom, and thelike), a linear or branched chain alkyl group (preferable carbon number:1 to 4, e.g., methyl group, ethyl group, propyl group, and the like), ahydroxyl group, and the like can be mentioned. Specific examples of thearyl group optionally having one or more substituents include a phenylgroup, an o-, m- or p-nitrophenyl group, an o-, m- or p-methoxyphenylgroup, an o-, m- or p-chlorophenyl group, an o-, m- or p-fluorophenylgroup, an o-, m- or p-tolyl group, and the like can be mentioned. As R¹,a phenyl group, a p-methoxyphenyl group, a p-chlorophenyl group and atolyl group are particularly preferable and as R², R³ and R⁴, a phenylgroup, a chlorophenyl group and a tolyl group are particularlypreferable.

In the formulae of the present invention, M is a hydrogen atom or analkali metal atom, and as the alkali metal atom, a potassium atom, asodium atom, and a lithium atom can be mentioned. Particularly, a sodiumatom and a potassium atom are preferable.

The azlactone compound represented by formula (1), which is used as astarting material in the present invention, can be obtained by, forexample, hydrolysis of a compound represented by the following formula(5) in water or a mixed solvent of water and an organic solvent, in thepresence of an alkali metal hydroxide. To be specific, for example, analkali metal hydroxide, preferably an aqueous solution thereof, is addedto compound (5) in a solvent, wherein the order of addition may bereverse or simultaneous:

wherein R¹ is as defined above, R⁵ and R⁶ are the same or different andeach is a methyl group or an ethyl group, and a wavy line indicates acis form a trans form, or a mixture thereof.

As the alkali metal hydroxide to be used, sodium hydroxide, potassiumhydroxide, lithium hydroxide, and the like can be mentioned, withpreference given to sodium hydroxide. The alkali metal hydroxide may beused in the form of a solid but preferably used as an aqueous solution,wherein the concentration thereof is within the range of 0.1N to 8N.

The amount of the alkali metal hydroxide to be used is generally 0.9-1.8molar equivalents, preferably 1-1.3 molar equivalents, relative to themoles of compound (5).

The solvent may be any as long as it does not inhibit the reaction and,for example, water, acetates (e.g., ethyl acetate, isopropyl acetate,isobutyl acetate, n-butyl acetate, and the like), acetonitrile,tetrahydrofuran (THF), N,N-dimethylformamide, acetone, and the like canbe mentioned. These may be used alone or in a combination of two or morekinds thereof, wherein a mixed solvent of water and an organic solventmiscible with water, such as acetonitrile, acetone and the like is morepreferable, and a mixed solvent of acetonitrile and water isparticularly preferable. The amount of the solvent to be used isgenerally 3- to 50-fold by weight, preferably 5- to 20-fold by weight,relative to the weight of compound (5). When an aqueous alkali metalhydroxide solution is used, the amount of water is included in theamount of the solvent. When an alcohol solvent (e.g., methanol, ethanol,isopropyl alcohol, and the like) is used, a side reaction such asazlactone ring opening of compound (5) and the like tends to occur, anduse of an alcohol solvent is not preferable.

The reaction temperature is within the range of from generally 0° C. tothe refluxing temperature of the solvent (preferably 0 to 30° C.) to beused. This reaction is completed within the above-mentioned temperaturerange in generally 60 min to overnight (preferably 2 hours to 20 hours).

After the completion of the reaction, compound (1) is present in theform of an alkali metal salt (M=alkali metal). When a free form ofcompound (1) (M=hydrogen atom) is to be isolated, an acid (e.g.,hydrochloric acid, sulfuric acid, etc.) is added to the reaction mixtureto adjust its pH to 3 to 5, and the mixture is subjected to conventionalisolation and purification methods, such as concentration of thereaction mixture or addition of a crystallization solvent to allowcrystal precipitation or silica gel column chromatography to isolate afree form of compound (1). As a crystallization solvent for the crystalprecipitation, water, ethers (e.g., diethyl ether, THF, and the like),acetone, acetonitrile, hydrocarbon solvents (e.g., toluene, benzene,hexane, heptane, and the like), halogen solvents (e.g., dichloromethane,dichloroethane, and the like), water or a mixed solvent thereof, and thelike can be mentioned. For isolation in the form of an alkali metalsalt, conventional isolation and purification methods, such asconcentration of a reaction mixture or addition of the above-mentionedcrystallization solvent to allow crystal precipitation, are applied toisolate an alkali metal salt of compound (1).

Since an alkali metal salt of compound (1) easily forms a hydrate, it ispreferably dried at a high temperature or dried by washing with a hightemperature slurry in an organic solvent to give an anhydrous crystal.

Compound (5) can be produced by a known method. For example, as inReference Examples 1-3 to be mentioned later, N-acylglycine representedby the formula: R¹C(═O)NHCH₂COOH, wherein R¹ is as defined above, isreacted with formamide represented by the formula: R⁵R⁶NCHO (whereineach symbol is as defined above) and phosphorus oxychloride to givecompound (5) (Ind. J. Chem., vol. 39B, pp. 688-693 (2000)). In addition,as shown in Reference Example 4 to be mentioned later, N-acylglycinerepresented by the formula: R¹C(═O)NHCH₂COOH (wherein R¹ is as definedabove) is reacted with formamidedimethylacetal represented by theformula: R⁵R⁶NCH(OMe)₂ (wherein each symbol is as defined above) in thepresence of N,N′-dicyclohexylcarbodiimide to give compound (4) (J.Heterocyclic Chem., vol. 34, pp. 247 (1997)).

In the present invention, an azlactone compound represented by formula(1) is reacted with an amidine compound represented by formula (2) or asalt thereof to give an aminopyrimidine compound represented by formula(3).

The solvent to be used for the reaction may be any as long as it doesnot inhibit the reaction and, for example, acetates (e.g., ethylacetate, isopropyl acetate, isobutyl acetate, n-butyl acetate, and thelike), alcohol, acetonitrile, acetone, tetrahydrofuran (THF),N,N-dimethylformamide, and the like can be mentioned. One or more kindsof these may be used in combination. Particularly, water-soluble organicsolvents such as acetonitrile, acetone, and the like are preferable. Ofthese, acetonitrile is more preferable. The amount of the solvent to beused is generally 3- to 50-fold by weight, preferably 5- to 20-fold byweight, relative to the weight of the azlactone compound (1). The amountof the amidine compound (2) or a salt thereof to be used is generally0.8 to 3.0 molar equivalents, more preferably 1.0 to 1.5 molarequivalents, relative to the moles of azlactone compound (1).

The reaction temperature is generally 0° C. to 100° C., preferably 30°C. to 80° C. This reaction is completed within the above-mentionedtemperature range in generally 1 to 30 hours, preferably 3 to 24 hours.

The type of salt of the amidine compound represented by formula (2) isnot particularly limited, but hydrochloride, sulfate, bromate, and thelike can be preferably mentioned. An amidine compound represented byformula (2) is preferably used in the form of a stable salt.

A method of isolating the obtained compound (3) after the completion ofthe reaction is not particularly limited, and various methods known tothose of ordinary skill in the art can be used. Generally, since acompound (3) is crystallized during the reaction, for example, acompound (3) can be isolated by, after the completion of the reaction,collecting the crystals by filtration and washing the crystals withwater, or, where necessary, collecting the crystals by filtration afteradding water to the reaction solution to partition a salt into a motherliquor, or, where necessary, washing the filtered crystals with waterand drying the separated crystals. In addition, before collection of thecrystals by filtration, the reaction solution may be concentrated,cooled, a poor solvent may be added and the like to perform furthercrystallization.

Among the compounds of formula (3), the compounds represented by formula(4) are novel substances:

wherein R¹ and R³ are as defined above.

As noted above, the compounds of formula (3) are useful as intermediatesfor preparing antineoplastic agents. In particular, the presentinvention provides methods for preparing compounds of formula (6):

wherein:

X is selected from the group consisting of a direct bond, C₁₋₄ alkylene,C₁₋₄ alkyleneoxy, C₁₋₄ alkoxyphenyl, or phenyl C₁₋₄ alkylene;Y is selected from the group consisting of a direct bond or C₁₋₂ alkyl;R⁷ is selected from the group consisting of (i) 5-15 membered cyclic orbranched chain heterocompound which includes one or two selected from agroup consisting of nitrogen, oxygen and sulfur and which is substitutedwith one or two selected from a group consisting of hydrogen, halogen,nitro, hydroxy, C₁₋₆ alkyl, C₃₋₆ alkenyl and halogen C₁₋₄ alkoxy, (ii)C₄₋₁₀ carbocyclic compound or (iii) hydroxy C₁₋₄ alkoxy;R⁸ is selected from the group consisting of 5-15 membered cyclic orbranched chain heterocompound which includes one or two selected from agroup consisting of nitrogen, oxygen and sulfur and which is substitutedwith one or two selected from a group consisting of hydrogen, hydroxy,halogen, nitro, hydroxy C₁₋₅ alkyl C₁₋₆ alkyl, C₃₋₆ alkenyl, and halogenC₁₋₄;R⁹ is selected from the group consisting of hydrogen, —C(O)R¹⁰, or—S(O)₂R¹¹;R¹⁰ and R¹¹ are each independently selected from the group consisting ofhydroxy, C₁₋₆ alkyl, C₃₋₇ cycloalkyl, C₃₋₆ alkenyl, halogen C₁₋₆ alkyl,halogen, C₂₋₆ alkenyl and C₁₋₄ alkoxy; or R¹⁰ and R¹¹ represent eachindependently:

and R¹² is selected from a group consisting of hydrogen, hydroxy, C₁₋₆alkyl, C₃₋₆ alkenyl, halogen, C₁₋₆ alkyl, halogen, nitro and C₁₋₄alkoxy. Such compounds and preferred embodiments are described in U.S.Pat. No. 6,380,206 which is incorporated herein by reference.

Other features of the invention will become apparent in the course ofthe following descriptions of exemplary embodiments which are given forillustration of the invention and are not intended to be limitingthereof.

EXAMPLES Reference Example 14-(N,N-dimethylaminomethylene)-2-methyl-5-oxazolinone

Phosphorus oxychloride (67.0 g, 437 mmol) and N,N-dimethylformamide(33.0 g, 451 mmol) were added to N-acetylglycine (20.0 g, 171 mmol) inan ice bath, and the mixture was stirred at 45° C. for 1.5 hours. Thereaction mixture was concentrated under reduced pressure and addeddropwise to 28% aqueous ammonia (150 ml) while maintaining thetemperature at not higher than 10° C. The reaction mixture was stirredfor 1 hour in an ice-bath and the precipitate was collected byfiltration. The obtained crystals were washed successively with waterand ethanol and dried to give the title compound as crystals (20.2 g,131 mmol).

¹H-NMR (CDCl₃) δ: 2.21 (3H, s), 3.18 (3H, m), 3.47 (3H, s), 6.96 (1H,s).

MS (ESI) m/z [MH]⁺ 155.2

Reference Example 22-benzyl-4-(N,N-dimethylaminomethylene)-5-oxazolinone

Chloroform (30.0 ml), phosphorus oxychloride (20.0 g, 130 mmol), andN,N-dimethylformamide (10.0 g, 137 mmol) were added to phenaceturic acid(10.0 g, 51.8 mmol) in an ice-bath, and the mixture was stirred at 45°C. for 1.5 hours. The reaction mixture was concentrated under reducedpressure and added dropwise to 28% aqueous ammonia (65 ml) whilemaintaining the temperature at not higher than 10° C. The mixture wasextracted with chloroform, and the organic layer was washed with waterand saturated brine and then concentrated to dryness. The concentratewas washed with isopropyl alcohol. The crystals were collected byfiltration, washed with isopropyl alcohol, and dried to give the titlecompound as crystals (9.90 g, 43.3 mmol).

¹H-NMR (CDCl₃) δ: 3.17 (3H, s), 3.48 (3H, m), 3.83 (2H, s), 6.97 (1H,s), 7.23-7.36 (5H, m)

MS (ESI) m/z [MH]⁺ 231.5

Reference Example 32-benzyl-4-(N,N-dimethylaminomethylene)-5-oxazolinone

Toluene (10.0 ml) and N,N′-dicyclohexylcarbodiimide (1.07 g, 5.19 mmol)were added to phenaceturic acid (1.00 g, 5.18 mmol), and the mixture wasstirred overnight at room temperature. The precipitate was removed byfiltration, N,N-dimethylformamide-dimethylacetal (0.68 g, 5.71 mmol) wasadded, and the mixture was stirred overnight. The reaction mixture waswashed with saturated brine and concentrated to dryness. Isopropylalcohol was added to the concentrate to allow crystallization and theprecipitated crystals were collected by filtration. The crystals werewashed with isopropyl alcohol and vacuum dried to give the titlecompound as crystals (0.78 g, 3.39 mmol).

Reference Example 4 4-hydroxymethylene-2-methyl-5-oxazolinone SodiumSalt•Anhydride

2N Aqueous sodium hydroxide solution (15 ml, 30.0 mmol) was added to asolution (50 ml) of4-(N,N-dimethylaminomethylene)-2-methyl-5-oxazolinone (4.00 g, 26.0mmol) in acetonitrile with ice-cooling, and the mixture was stirredovernight. Water was evaporated, acetonitrile (30 ml) was added, and themixture was stirred at 60° C. for 1 hour. The precipitate was collectedby filtration, washed with acetonitrile, and vacuum dried at 80° C. togive the title compound as white crystals (3.65 g, 24.5 mmol).

¹H-NMR (DMSO-d₆) δ: 2.00 (3H, s), 8.67 (3H, s)

MS (API-ES) m/z [MH]⁺ 126.1

Reference Example 5 2-benzyl-4-hydroxymethylene-5-oxazolinone SodiumSalt•Monohydrate

1N Aqueous sodium hydroxide solution (53 ml, 53.0 mmol) was added to asolution (120 ml) of2-benzyl-4-(N,N-dimethylaminomethylene)-5-oxazolinone (10.8 g, 46.9mmol) in acetonitrile with ice-cooling, and the mixture was stirredovernight. Acetonitrile was evaporated to allow precipitation ofcrystals with ice-cooling. The precipitate was collected by filtrationand vacuum dried to give the title compound as white crystals (5.99 g,26.6 mmol). Differential Scanning Calorymetry (DSC) and Thermogravimetry(TG) were performed using a thermal analysis instrument (RIGAKUCORPORATION, TAS-200). As a result, an endothermal peak was found at121.4° C. and a weight decrease was observed at 116.1 to 126.9° C.

¹H-NMR (DMSO-d₆) δ: 3.66 (2H, s), 7.22-7.32 (5H, m), 8.71 (1H, s)

MS (ESI) m/z [MH]⁻ 202.1

Reference Example 6 2-benzyl-4-hydroxymethylene-5-oxazolinone SodiumSalt•Anhydride

1N Aqueous sodium hydroxide solution (5 ml, 5.00 mmol) was added to asolution (10 ml) of2-benzyl-4-(N,N-dimethylaminomethylene)-5-oxazolinone (1.00 g, 4.34mmol) in acetonitrile with ice-cooling, and the mixture was stirredovernight. The reaction mixture was concentrated to dryness, andacetonitrile (5 ml) was added. The precipitate was collected byfiltration and dried at 10° C. for 2 hours to give the title compound aswhite crystals (0.90 g, 4.00 mmol). DSC and TG were performed using athermal analysis instrument. As a result, endothermal peak and clearweight change were not observed up to 220° C.

¹H-NMR (DMSO-d₆) δ: 3.66 (2H, s), 7.22-7.32 (5H, m), 8.71 (1H, s)

MS (ESI) m/z [MH]⁻ 202.1

Reference Example 7 2-benzyl-4-hydroxymethylene-5-oxazolinone

2N Aqueous sodium hydroxide solution (0.92 ml) was added to a solution(15 ml) of 4-N,N′-dimethylaminomethylene-2-benzyl-5-oxazoline (350 mg,6.65 mmol) in acetonitrile with ice-cooling, and the mixture was stirredovernight at room temperature. The reaction mixture was concentrated toallow evaporation of acetonitrile, washed with ethyl acetate (5 ml), andadjusted to pH 4 with 1N hydrochloric acid with ice-cooling. Theprecipitate was collected by filtration, washed with water, and vacuumdried to give the title compound as crystals (1.03 g, 5.07 mmol).

¹H-NMR (DMSO-d₆) δ: 3.92 (2H, s), 7.29-7.38 (5H, m), 7.68 (1H, s)

MS (ESI) m/z [MH]⁻ 202.3

Example 1

Acetonitrile (15 ml) was added to2-benzyl-4-hydroxymethylene-5-oxazolone sodium salt (1.00 g, 4.44 mmol)and O-methylisourea hydrochloride (0.49 g, 4.44 mmol), and the mixturewas stirred overnight at 80° C. The mixture was concentrated underreduced pressure, water (5 ml) was added, and the mixture was stirred atroom temperature for 1 hour. Then, the precipitate was collected byfiltration and vacuum dried to give2-methoxy-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine (0.94 g, 3.64mmol).

¹H-NMR (DMSO-d₆) δ: 3.75 (2H, s), 3.85 (3H), 7.23-7.31 (5H, m), 8.40(1H, s), 9.32 (1H, s), 12.66 (1H, brs)

MS (ESI) m/z [MH]⁺ 259.9

Example 2

Acetonitrile (20 ml) was added to2-methyl-4-hydroxymethylene-5-oxazolone sodium salt (1.00 g, 6.71 mmol)and O-methylisourea hydrochloride (0.74 g, 6.71 mmol), and the mixturewas stirred at 80° C. for 2 days. The mixture was concentrated, andmethanol (5 ml) and water (3 ml) were added. The mixture was stirred atroom temperature for 1 hour. Then, the precipitate was collected byfiltration and vacuum dried to give2-methoxy-6-oxo-5-acetylamino-1,6-dihydropyrimidine (0.91 g, 4.97 mmol).

¹H-NMR (DMSO-d₆) δ: 2.06 (3H, s), 3.85 (3H), 8.36 (1H, s), 9.14 (1H, s),12.62 (1H, brs)

MS (ESI) m/z [MH]⁻ 182.1

Example 3

O-Methylisourea hydrochloride (0.11 g, 1.0 mmol) was dissolved inmethanol (2 ml), and 28% sodium methoxide (0.19 g, 1.0 mmol) was added.Acetonitrile was added, and the mixture was concentrated.2-Benzyl-4-hydroxymethylene-5-oxazolone (0.203 g, 1.00 mmol) was added,and the mixture was stirred overnight at 80° C. Water (3 ml) was added,and the mixture was stirred at room temperature for 1 hour. Then, theprecipitate was collected by filtration and vacuum dried to give2-methoxy-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine (0.16 g, 0.62mmol). The values of the shift in ¹H-NMR were the same as those inExample 1.

Example 4

Acetonitrile (6 ml) was added to 2-benzyl-4-hydroxymethylene-5-oxazolonesodium salt (0.50 g, 2.22 mmol) and S-methylisourea sulfate (0.34 g,1.22 mmol), and the mixture was stirred overnight at 80° C. The mixturewas cooled and the precipitate was collected by filtration. The crystalswere washed with water, and the obtained crystals were vacuum dried togive 2-methylthio-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine (0.51g, 1.91 mmol).

¹H-NMR (DMSO-d₆) δ: 2.74 (3H, s), 3.77 (2H, s), 7.23-7.32 (5H, m), 8.60(1H, s), 9.43 (1H, s), 13.03 (1H, brs)

MS (ESI) m/z [MH]⁻ 274.0

Example 5

Acetonitrile (6 ml) was added to 2-methyl-4-hydroxymethylene-5-oxazolonesodium salt (0.10 g, 0.67 mmol) and S-methylisourea sulfate (0.10 g,0.37 mmol), and the mixture was stirred overnight at 80° C. The mixturewas cooled, and the precipitate was collected by filtration. Thecrystals were washed with water and the obtained crystals were vacuumdried to give 2-methylthio-6-oxo-5-acetylamino-1,6-dihydropyrimidine(0.09 g, 0.46 mmol).

¹H-NMR (DMSO-d₆) δ: 2.08 (3H, s), 2.48 (3H, s), 8.58 (1H, s), 9.27 (1H,s), 12.96 (1H, brs)

MS (ESI) m/z [MH]⁻ 197.9

Example 6

Acetonitrile (2 ml) was added to 2-benzyl-4-hydroxymethylene-5-oxazolonesodium salt (61 mg, 0.27 mmol) and N-dimethylguanidine sulfate (40 mg,0.15 mmol), and the mixture was stirred overnight at 85° C. Water (3 ml)was added, and the mixture was stirred at room temperature for 1 hour.Then, the precipitate was collected by filtration and vacuum dried togive 2-dimethylamino-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine (45mg, 0.17 mmol).

¹H-NMR (DMSO-d₆) δ: 2.99 (6H, s), 3.71 (2H), 7.23-7.31 (5H, m), 8.21(1H, s), 9.09 (1H, brs)

MS (ESI) m/z [MH]⁻ 271.2

Example 7

Acetonitrile (6 ml) was added to 2-benzyl-4-hydroxymethylene-5-oxazolonesodium salt (0.50 g, 2.22 mmol) and benzamidine hydrochloride (0.35 g,2.22 mmol), and the mixture was stirred overnight at 80° C. Water (3 ml)was added, and the mixture was stirred. The precipitate was collected byfiltration, and the obtained crystals were washed with water and vacuumdried to give 2-phenyl-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine(0.51 g, 1.67 mmol).

¹H-NMR (DMSO-d₆) δ: 3.84 (2H, s), 7.25-7.34 (5H, m), 7.51 (3H, m), 8.06(2H, d, J=7.0 Hz), 8.86 (1H, s), 9.64 (1H, s), 13.05 (1H, brs)

MS (ESI) m/z [MH]⁺ 306.5

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

All patents and other references mentioned above are incorporated infull herein by this reference, the same as if set forth at length.

1-7. (canceled)
 8. A compound represented by formula (4) or saltthereof:

wherein R¹ is an alkyl group optionally having one or more substituents,an aryl group optionally having one or more substituents or an aralkylgroup optionally having one or more substituents; and R³ is an alkylgroup optionally having one or more substituents, an aryl groupoptionally having one or more substituents, or an aralkyl groupoptionally having one or more substituents.
 9. The compound or saltthereof of claim 8, wherein R¹ is a linear or branched chain alkyl grouphaving 1 to 20 carbon atoms, which optionally has one or moresubstituents, an aryl group having 6 to 20 carbon atoms, whichoptionally has one or more substituents or an aralkyl group optionallyhaving one or more substituents, wherein the aryl moiety of said aralkylgroup is an aryl group having 6 to 12 carbon atoms and the alkyl moietyof said aralkyl group is a linear or branched chain alkyl group having 1to 6 carbon atoms.
 10. The compound or salt thereof of claim 9, whereinR¹ is a methyl group, an ethyl group, or a benzyl group.
 11. Thecompound or salt thereof of claim 8, wherein R³ is a linear or branchedchain alkyl group having 1 to 20 carbon atoms, which optionally has oneor more substituents, an aryl group having 6 to 20 carbon atoms, whichoptionally has one or more substituents, or an aralkyl group optionallyhaving one or more substituents, wherein the aryl moiety of said aralkylgroup is an aryl group having 6 to 12 carbon atoms and the alkyl moietyof said aralkyl group is a linear or branched chain alkyl group having 1to 6 carbon atoms.
 12. The compound or salt thereof of claim 11, whereinR³ is a methyl group, an ethyl group, a phenyl group, a chlorophenylgroup, a tolyl group, or a benzyl group.
 13. The compound or saltthereof of claim 8, which is selected from the group consisting of2-methoxy-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine,2-methoxy-6-oxo-5-acetylamino-1,6-dihydropyrimidine, and a salt thereof.14. The compound or salt thereof of claim 8, which is2-methoxy-6-oxo-5-phenylacetylamino-1,6-dihydropyrimidine or a saltthereof.
 15. The compound or salt thereof of claim 8, which is2-methoxy-6-oxo-5-acetylamino-1,6-dihydropyrimidine or a salt thereof.16-20. (canceled)